276 Unii'( rsitij of Culij'ornia I'liblicdiioiis in Botany | \<h.. 7 



It seems eleai* from llic results iiichuli'd in tlic aliove table that 

 tlic root areas of the two species of Ilaplopappus examined contain 

 ai)i))'ecialih' (|uaiitities of i-ul)l)er. In the case of //. ericoides the 

 parts above tin' soil line are strikingly detieient in rubber as compared 

 with the roots. Indeed, in the extremities of the root the percentage 

 is often highest and decreases as one passes upward towards the soil 

 line. The regional distribution in ericoides is, thus, the reverse of 

 that found in the various varieties of Chrysothannitis. 



In //. tuiiiKS, on the other hand, stem and root aj)pear to Ix-ai' 

 ecjual (luantities of rubber. The evidence here is o])vi()usly fragmen- 

 tary but the above statement holds rather strictly for 206, and in the 

 case of 256 the stem probably bears a maximum (juantity for this 

 plant and it might be assumed that the root, if anal^'zed, would show 

 an approximately equal amount. 



It appears, then, that three types of regional distribution of con- 

 tained rubber are shown by the plants which we have examined in 

 the course of the entire investigation. In the first place, the maxinnnn 

 quantity is borne by the stem. This is peculiar to the distribution of 

 Chr^-sil. In the second place, root and stem bear equal amounts. 

 This condition obtains in Haplopappiis nauus. Finally, we have the 

 case in which the root carries almost the entire amount of rubber 

 borne by the plant, //. ericoides. This seems a rather remarkable 

 situation and one which would repay further investigation. In par- 

 ticular it would be important to examine in detail the distribution 

 of rubber in the other species of Ilaplopappus not investigated in 

 this particular connection by us. 



111. SPECIES IN WHICH NO KUBBER WAS FOUND 



In the course of the investigation reported on in the foregoing 

 pages a miscellaneous collection of plants was made as opportunity 

 offered and these have been examined histologically for rubber con- 

 tent wdth the result that rubber was located in certain cases but only 

 in species of Chrysoihammis or of related genera. This occurrence 

 has been noted in the preceding list but it now remains to enumerate 

 those species in which no rubber could be detected with certainty. 

 This list is given as it may be of some service in case a more extensive 

 survey is undertaken. As in the preceding report, the numbers refer 

 to field notes and have been assigned merely for convenience of refer- 

 ence. Tin- locality imiitioned in each case is the jilace of collection. 



